Patent application title: DEVICE FOR ADDING FLUID TO A LIQUID

Abstract:

Device for adding a fluid to a liquid, for example of gas and/or particles
to liquid metal. A rotor is rotated immersed in the liquid, comprising a
hollow rotational body 10 with a first inner annular wall 16 with at
least one radial opening 18 from a central, cylindrical chamber 19 and
with an opening directed downwards. The rotational body is carried by a
generally vertical shaft 12 which is connected to a powering unit and
which may be arranged to lift the rotational body out of respectively
lower it into the liquid. Outside the central annular wall 16 of the
rotational body 10 a further annular wall 14 which forms an annular
chamber 17 is arranged, which communicates with the central chamber
through the one or more radial openings 18. Advantages are achieved by
that the one or more of the radial openings 18 are arranged in the lower
part of the inner annular wall 16 of the rotational body, in a area which
projects down under the surrounding additional annular wall 14.

Claims:

1. Device for adding a fluid to a liquid, for example of gas and/or
particles to liquid metal, with a rotor which is driven immersed in the
liquid and which comprises a hollow rotational body (10) with a first,
inner annular wall (16) with at least one radial opening (18) from a
central, cylindrical shaped hollow room (19) with an opening directed
downwards, as the rotational body is carried by a generally vertical
shaft (12) and is connected to a driving unit and which may be arranged
to lift the rotational body out, respectively lower it into the liquid,
where it outside the central annular wall (16) of the rotational body
(10) is arranged a further annular wall (14) which forms an annular
chamber (17), which communicates with the central room through the one or
more radial openings (18), characterized in that the one or more radial
openings (18) are arranged in the lower part of the inner annular wall
(16) of the rotational body, in an area projecting below the surrounding
additional annular wall (14).

2. Device according to claim 1, characterized in that the hollow
rotational body (10) comprises more than two generally concentric annular
walls (21-24), providing two or more annular rooms (25, 26, 27) outside
the central hollow room, whereby the fluid is supplied to the central
hollow room (19) and further to the annular rooms (21-24) and to the
liquid via at least one opening (18) in each annular wall (21-24), as the
radial openings (18) are arranged in the lower part of each annular wall.

3. Device according to claim 1, characterized in that the openings (18) in
the annular walls (21-24) are placed mutually displaced in the peripheral
direction and/or axially related to each other.

4. Device according to claim 1, characterized in that four openings (18)
are arranged in each annular wall.

5. Device according to claim 1, characterized in that it comprises four
annular walls (21-24, FIG. 2).

Description:

[0001]The invention relates to a device as described in the introductory
part of claim 1, for adding fluid to a liquid. The term "fluid" should
here be understood as a gas, a liquid or a mix of these, possibly with
the addition of particles. Some particle masses may also be treated and
transported as a fluid.

BACKGROUND

[0002]For some purposes there is a need for treatment of liquids, such as
melted metals, by addition of a fluid. Particularly actual fluids in
connection with metal melting are a gas and/or a particular material. For
this purpose it is known to use a device with a rotor which is submerged
in the liquid and where a fluid, that is gas and/or particles, is added
through the inner part of the rotor.

[0003]Such a rotor may comprise a hollow rotational body with openings in
the bottom and the side, which is mounted and driven via a shaft by a
driving unit and that is arranged to be lifted out of and lowered into
the liquid. When a gas reacts with a liquid, the speed of the reaction
will be a function of the surface of the gas bubbles that is in inverse
ratio with the diameter of the gas bubbles. That is, gas bubbles with a
small diameter are desired.

[0004]Generally there is a desire for rotors in treatment of liquid, in
particular treatment of melted metals, that the addition of gas or a
particular material is effective. At the other side, there is also a
desire not to create too much stirring or turbulence which causes a
turbulent surface and whirls in the liquid and thereby causes an
increased addition of undesirable gas from the environment (atmosphere).

[0005]It is previously known equipment for treatment and addition of a
particular material in a liquid as mentioned above. Thus it is known from
the inventors Norwegian patent 155447 a rotor for treatment and addition
of material in a liquid where the rotor is constituted by a symmetric
rotational hollow body, and where the material is added to the liquid via
a bore in the rotor shaft and further out through a hole in the side of
the hollow body together with the liquid, which due to the centripetal
force is sucked in through an opening in the bottom and circulate through
the body.

[0006]From the inventors own patent Norwegian patent application 19983142
it appears a solution by rotors for treatment of liquid where the
efficiency when intermixing gas or particles into a liquid is close to
doubled, but where the stirring is maintained unchanged related to the
design shown in NO 155447. Further it is reached a solution by rotors
where the use of gas/particles is less than the half.

[0007]From the Norwegian patent 307289 it is known a device for addition
of a fluid to a liquid, for example of gas and/or particles to a liquid
metal, with a rotor which is driven immersed in the liquid and which
comprises a hollow rotational body with a first inner annular wall and at
least one radial opening from a centrally, cylinder shaped hollow room
with an opening facing downwards, as the rotational body is carried by a
generally vertical shaft which is connected to a driving unit and which
may be arranged to lift the rotational body out, respectively lower it
into the liquid, where it outside the central annular wall of the
rotational body is arranged an additional annular wall which forms an
annular chamber, which communicates with the central chamber through the
one or more radial openings.

[0008]A disadvantage of this design of the rotor is that liquid which
contains bubbles or powder, and which comes out of the central chamber,
comes into an annular chamber with a narrow opening and small volume for
mixing the bubbles or powder into the liquid. What would have been
satisfactory in a liquid with low specific weight, for example water,
does not work satisfactory in liquid metal, for example aluminium.

Purpose

[0009]The main purpose of the invention is to create such a device in
connection with a rotor used for addition of a fluid, where the
efficiency of the intermixture is further improved. It is particularly
desirable to increase the efficiency when adding gas or gas mixtures
containing particles, where big size of the bubbles reduces the
efficiency.

The Invention

[0010]The invention is described in claim 1. The one or more radial
openings is arranged in the lower part of the inner annular wall of the
rotational body, in an area which extends down under the surrounding
further annular wall.

[0011]By the fact that the added fluid passes the annular wall inn this
way, the intermixture becomes more effective.

[0012]Particularly this is valid for gas, where more openings means
smaller bubble diameter.

[0013]The rotor of the device according to the invention will, when gas
bubbles are supplied, provides that the gas bubbles emerging from the
inner row of holes will be sucked into the one ore more other annular
rooms so that the gas is treated several times. A corresponding increase
of the intermixture will be achieved when supplying other fluids.

[0014]The dependant claims 2-5 describes advantageous features of the
invention.

EXAMPLE

[0015]The invention will in the following be described more closely by
help of example and with reference to the accompanying drawings where:

[0016]FIG. 1 shows an axial intersection through one embodiment of the
invention with one extra annular wall, while

[0017]FIG. 2 shows a corresponding axial intersection through a further
embodiment of a rotor according to the invention with more extra inner
annular walls.

[0018]FIG. 1 shows an example of a rotor 10 according to the invention. It
comprises a rotational symmetrical main part 11, preferably cylindrical,
which is carried by an upwards projecting driven rotor shaft 12 with
vertical axis and with a central channel 13.

[0019]At the outer edge of the main part 11 there is an outer annular wall
14 which projects downwards with four evenly distributed side holes 15.
Between the outer annular wall 14 and an inner concentric annular wall 16
an annular chamber 17 is arranged. The inner concentric annular wall 16
projects downwards below the outer annular wall 14 and has in the
projecting area, four evenly distributed side holes 18. Thereby the side
holes 18 will end below the mouth of the annular chamber 17. The inner
annular wall forms a cylindrical chamber 19 which is supplied with fluid
through the central channel 13. The fluid may be a gas and/or particle
formed material.

[0020]The rotor 10 operates in the following way: It is lowered into a
liquid, for example a liquid metal, and is rotated. The liquid will then,
due to the rotation of the rotor and thereby the centripetal force which
is generated in the fluid, be sucked up in the inner chamber 19 and the
annular chamber 17. Gas and/or particles which are supplied through the
channel 13 in the rotor shaft 12 will be pressed through the holes 18 out
in the surrounding liquid. At the same time, due to the buoyancy and
suction, a large part of gas and particles will enter into the annular
chamber 17 and emerge through the side holes 15.

[0021]Moreover the invention is not limited to one extra annular wall, but
may be provided with two or more additional annular walls. FIG. 2 shows
an example of a rotor 20 where it is used one outer annular wall 21 and
three stepped downwards projecting additional annular walls 22, 23, 24.
Between these annular walls three annular chambers are formed, an inner
annular chamber 25, an intermediate chamber 26 and an outer chamber 27.

[0022]The annular walls 22-24 have four side holes 18 in the lower part,
in a similar way as in the example embodiment in FIG. 1.